EP0210278B1 - Anordnung zum nachweis von durch ermüdung verursachten rissen - Google Patents

Anordnung zum nachweis von durch ermüdung verursachten rissen Download PDF

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Publication number
EP0210278B1
EP0210278B1 EP86900849A EP86900849A EP0210278B1 EP 0210278 B1 EP0210278 B1 EP 0210278B1 EP 86900849 A EP86900849 A EP 86900849A EP 86900849 A EP86900849 A EP 86900849A EP 0210278 B1 EP0210278 B1 EP 0210278B1
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EP
European Patent Office
Prior art keywords
crack
reference line
test piece
distal end
fatigue
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP86900849A
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English (en)
French (fr)
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EP0210278A4 (de
EP0210278A1 (de
Inventor
Eiichi Makabe
Mitsuaki Uesugi
Masaichi Inomata
Kyusuke Maruyama
Kenji Iwai
Kazuo Sano
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JFE Engineering Corp
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Nippon Kokan Ltd
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Publication date
Priority claimed from JP1209885A external-priority patent/JPS61170603A/ja
Priority claimed from JP23902685A external-priority patent/JPS6298203A/ja
Priority claimed from JP23902585A external-priority patent/JPS6298202A/ja
Application filed by Nippon Kokan Ltd filed Critical Nippon Kokan Ltd
Publication of EP0210278A1 publication Critical patent/EP0210278A1/de
Publication of EP0210278A4 publication Critical patent/EP0210278A4/de
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/024—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by means of diode-array scanning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/006—Crack, flaws, fracture or rupture
    • G01N2203/0062—Crack or flaws
    • G01N2203/0066—Propagation of crack
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0073—Fatigue
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/027—Specimens with holes or notches

Definitions

  • the present invention relates to a method of detecting a fatigue crack position on a notched test piece according to claim 1, and a fatigue crack position detection apparatus according to claim 3.
  • Measurement of fatigue crack position of a metal material uses notched test piece 10 in which fatigue crack 12 is formed, as shown in Fig. 2.
  • the shape and size of piece 10 are defined in e.g., B,S, 5762:1979 (Methods for crack opening displacement testing).
  • Test piece 10 is defined such that crack 12 having a predetermined length is formed from the bottom portion of notch 11 formed in the central portion of piece 10. During formation of crack 12, a load must be applied on test piece 10 while observing the length, i.e., the distal end position of crack 12.
  • noncontact detection methods include a method for optically monitoring crack 12 and a method for detecting a magnetic change caused by crack 12 as a change in eddy current, if piece 10 is a magnetic substance.
  • the noncontact detection methods include a method for optically monitoring crack 12 and a method for detecting a magnetic change caused by crack 12 as a change in eddy current, if piece 10 is a magnetic substance.
  • the detection result varies in accordance with the magnetic characteristics of the piece, and a crack position cannot be precisely detected. Therefore, demand has arisen for an apparatus which can precisely and easily detect a crack position by an optical method.
  • the JP-B2-57-5286 US-A 4 242 702 discloses a technique for recognizing the position of an object, in particular to a pattern matching technique, and relates to a method for examining the position of an object and to an apparatus which detects the coordinates of the position of the object from the outline thereof and which examines the positional displacement of the object.
  • the present invention has as its object the solution to the above problems so that the distal end position of a crack formed in a notched test piece can be detected.
  • the number of "white” or “black” pixels is added up vertically or horizontally, and the frequency distribution in each direction is calculated. Then, the location of the object is computed on the basis of the maximum value or the predetermined threshold value of the frequency distribution curve, this location is read as the coordinates of the position of the examined object, and the displacement of the examined object is examined by comparing the coordinates with the basic scope of the preset image.
  • the GB-A-2 108 684 does not disclose the use of a reference line. Further, it does not suggest the method step of masking averaged luminance levels obtained and of using a strobe illumination device. This means that both the method and apparatus as disclosed in the GB-A-2 108 684 cannot be compared with the present invention at all.
  • microscopes 20 and 21 are arranged to set both the surfaces of notched test piece 10 within their fields of view.
  • Optical images obtained by microscopes 20 and 21 are scanned by industrial TV camera (ITV) heads 22 and 23.
  • the operations of ITV camera heads 22 and 23 are respectively controlled by ITV camera controllers 24 and 25.
  • Both surfaces of test piece 10 are obliquely irradiated with light from light sources 26 and 27, respectively.
  • notch 11 is formed in the central portion of its lower side, and crack 12 having a predetermined length is formed from the bottom portion of notch 11.
  • Crack 12 is formed by, e.g., applying a load from a side surface opposite notch 11 in the direction of arrow A while holding the two ends of piece 10.
  • the length, i.e., the distal end, of crack 12 is detected by a distance between line 13 scribed with a diamond scriber and itself. It is preferable that the surface on which line 13 is scribed is sufficiently polished to obtain a mirror surface.
  • Fig. 3 illustrates this portion in detail.
  • Optical axis G of microscope 21 is substantially perpendicular to the surface of test piece 10, and light R from light source 27 is incident on the surface of 10 at predetermined angle ⁇ with respect to optical axis G. Therefore, microscope 21 receives only light reflected by portions, e.g., line 13, scratches, and the like, which irregularly reflect incident light R. Note that the direction of line 13 preferably coincides with the horizontal scanning directions of ITV camera heads 22 and 23. ITV camera heads 22 and 23 scan images of test piece 10 which are enlarged through microscopes 20 and 21 under the control of ITV camera controllers 24 and 25, respectively.
  • Video signals from heads 22 and 23 are supplied to signal processor 30 respectively through controllers 24 and 25, and are then supplied to line detection means 32 and crack distal end position detection means 33 through camera switch 31.
  • reference numeral 34 denotes a sync signal generator for supplying a sync signal to controllers 24 and 25 and switch 31.
  • Line detection means 32 integrates the luminance level of the video signal in the same direction as that of line 13 for each raster to obtain a maximum luminance level for one frame, thereby detecting a line position from a raster position at which the maximum luminance level is obtained.
  • Line detection means 32 comprises horizontal integrating circuit 35 and integrated value peak position detector 36.
  • Crack distal end position detection means 33 converts the video signal into a binary signal and, thereafter, checks if a high level value is continuously generated from image data obtained from the binary signal and satisfies a given continuity condition, thereby detecting crack 12.
  • Crack distal end position detection means 33 comprises filter circuit 37, binary-coding circuit 38 and noise removing circuit 39.
  • Reference numeral 42 denotes a distance detector.
  • Distance detector 42 obtains a distance between the line position and the crack distal end position obtained by means 32 and 33. Crack image 12d, line image 13d, and the distance therebetween are displayed on display 41, as shown in Fig. 3.
  • the apparatus of the present invention comprises stop distance setting circuit 42 prestoring a set value of a distance between line 13 and the crack distal end position for stopping a fatigue test machine (not shown), and fatigue test machine stop signal generator 43 for supplying a stop signal to the fatigue test machine.
  • ITV camera heads 22 and 23 set images of line 13 and crack 12 on the surfaces of test piece 10 enlarged by microscopes 20 and 21 within their fields of view. Image positions and the like are adjusted to obtain an image shown in Fig. 4(a). Illuminances of light sources 26 and 27 are varied to uniformly scan line 13 and crack 12 in white light. Note that the black and white portions of the image in Fig. 4(a) are reversed for the sake of simplicity.
  • the video signals of the images are supplied to line detection means 32 and crack distal end position detection means 33 through ITV camera controllers 24 and 25 and camera switch 31.
  • Line detection means 32 obtains an integrated value of luminance level of the video signal for each horizontal scanning period, i.e., for each raster. More specifically, the integrated value of the luminance level is obtained in the same direction as that of line 13 in the image shown in Fig. 4(a). Luminance distribution In vertical direction V shown in Fig. 4(b) is then obtained. Integrated value peak position detector 36 detects the maximum luminance level from the luminance distribution to obtain the position of line 13. Since crack 12 is also scanned in white light, it has a high luminance level. However, the luminance level by crack 12 is negligible since integration is performed in the direction of line 13.
  • vertical size V of each field of view of ITV camera heads 22 and 23 is 5 mm, and the number of scanning lines of heads 22 and 23 is 480. Since an interlaced scanning system is adopted, one frame consists of 240 rasters. Therefore, the width of a raster is about 20 ⁇ m. In contrast to this, since the width of line 13 is about 100 ⁇ m, an image signal of line 13 can be obtained within four to five rasters.
  • a video signal obtained from ITV camera head 22 is selected by camera switch 31, and is then supplied to horizontal integrating circuit 35 and filter circuit 37.
  • Horizontal integrating circuit 35 integrates the luminance level of each of 240 rasters, and sequentially stores the integrated value in a memory having 240 address positions corresponding to the number of rasters.
  • the luminance level integrated values for the respective rasters stored in the memory are sequentially supplied to integrated value peak position detector 36 for every address of the memory, and the peak value is detected. Assume that peak values are obtained between the 96th raster to 100th raster of the 240 rasters (counted from the upper raster).
  • Detector 36 can hold addresses in this internal, i.e., the 96th to 100th memory addresses.
  • the above operation can be easily realized by constituting line detection means 32 by a microcomputer.
  • Crack distal end position detection means 33 performs the following operation.
  • the video signal on line A-A' shown in Fig. 4(a) has a high level corresponding to crack portion P, as shown in Fig. 5(a).
  • the video signal is passed through high-pass filter circuit 37 to remove a DC component therefrom so as to emphasize crack portion P and not to be influenced by a change in the entire luminance level (e.g., caused by changing an object to be measured).
  • the video signal passed through high-pass filter circuit 37 has a waveform, e.g., as shown in Fig. 5(b), and is supplied to binary-coding circuit 38 to be binary-coded, thereby detecting pulse signal P' corresponding to crack 12.
  • binary-coding circuit 38 detects the maximum value of the video signal for each raster and, therefore, determines that crack 12 is present at a position on the raster at which the maximum value is detected. However, it is nonsence to detect the maximum level on a scanning line on which no crack 12 is present. Thus, threshold level L is set and maximum value detection is performed with respect to signals exceeding threshold level L.
  • Fig. 5(c) shows an image obtained from the binary signal.
  • threshold level L does not satisfactorily extract only crack 12, and the resultant image data includes a noise component.
  • the noise component includes scratches formed when piece 10 is polished.
  • the same waveform as that of the crack portion is formed and is erroneously detected as noise.
  • noise removing circuit 39 uses window W shown in Fig. 6(a). Window W extends vertically and horizontally in given lengths from given point B. If the number of high levels (maximum values) within window W, i.e., the density of a point within window W exceeds a certain value, the point is determined as a part of crack 12; otherwise, it is determined as a noise component and erased.
  • Fig. 6(b) shows binary signal levels in noise component portion Q1 shown in Fig. 7, and reveals that high-level portions (indicated by black dots in Fig. 6(b)) are discontinuous.
  • Fig. 6(c) shows portion Q2 of crack 12, and reveals that the high-level portions are continuously generated.
  • the video signal obtained from binary circuit 38 for each raster as shown in Fig. 5(b) is supplied to noise removing circuit 39.
  • the input video signal is sampled using sampling pulses having a pulse rate which divides one horizontal scanning period (1H) into 256 subperiods, and the sampling outputs are stored in a dot memory having 256 horizontal address positions and 240 vertical address positions.
  • the video signal for one frame stored in the dot memory is subjected to noise removal using a 7 (row dots) ⁇ 15 (column dots) partial memory as window W. More specifically, if the number of black dots within window W is below a predetermined value, as shown in Fig. 6(b), the black dots within window W are determined as noise components and are erased.
  • the video signal output from binary circuit 38 i.e., obtained from the state shown in Fig. 5(b) is sampled as 256 digital data, and then input to circuit 39.
  • noise removing circuit 39 256 stages of first and second registers are horizontally arranged, and data for 240 vertical rasters are sequentially input to the first and second registers. The contents of the first and second registers are compared at every stage. If there is data corresponding to the crack in the vertical direction, the contents of the first and second registers coincide with each other, and are held as crack data.
  • the above operation is sequentially performed downward with respect to data for 240 rasters, and a vertical memory address corresponding to a raster from which a coincidence is first found is used as position data of distal end 12a of the crack.
  • the line position and crack distal end position obtained by means 32 and 33 are supplied to distance detector 40.
  • a distance between line 13 and crack distal end position 12a is calculated by distance detector 40 as a difference between their addresses, and is displayed on display 41.
  • the distance is compared with a distance set in stop distance setting circuit 42. When the calculated distance is smaller than the set distance, stop signal generator 43 sends fatigue test stop signal K to the fatigue test machine, thereby releasing a load applied on test piece 10.
  • the maximum luminance level is obtained by line detection means 32 from the video signals of test piece 10 scanned through microscopes 20 and 21 to detect the position of line 13.
  • crack distal end position detection means 33 converts the video signal into a binary signal, and then checks continuity of a high level to extract the image of crack 12, thereby detecting the position of crack distal end 12a.
  • Distance detector 40 then calculates the distance between line 13 and crack distal end position 12a with reference to the position of line 13 and the crack distal end position. Therefore, the following effects can be provided.
  • the above operation can be individually performed for the two ITV cameras.
  • distances of two cracks and lines are calculated from images obtained by the two ITV cameras and their averaged value is detected to obtain the distance.
  • an automatic measuring apparatus which can automatically measure a crack distal end position of a notched test piece with high precision can be provided.
  • the width of line 13 is about 100 ⁇ m, and the width of a raster is 20 ⁇ m, and a video signal corresponding to line 13 is obtained from four to five rasters. Therefore, the most proper distance between line 13 and crack distal end 12a is one between the raster closest to crack distal end 12a among four to five rasters including the video signal of line 13, i.e., the lower end of line 13 and crack distal end 12a.
  • Fig. 8 shows an embodiment capable of detecting the distance between the lower end of line 13 and crack distal end 12a.
  • the same reference numerals in Fig. 8 denote the same parts as in Fig. 1, and a detailed description thereof will be omitted.
  • line detection means 32A adopts the method of the above embodiment, and obtains average luminance levels in the same direction as that of line 13 from the video signals for the respective rasters obtained by scanning test piece 10 during the fatigue test.
  • the average luminance levels are binarized using an optimal position for the fatigue test in the widthwise direction of the line (in this case, threshold level Q corresponding to the lower end position of line 13, as shown in Fig. 9(b)).
  • the average luminance levels are then masked by the binary data to detect an optimal position for the fatigue test.
  • means 32A comprises horizontal integrating circuit 35 for obtaining the average luminance levels for the respective rasters in the same direction as that of line 13 from the video signals from ITV camera heads 22 and 23, binary circuit 44 for binary-coding the average luminance levels obtained from circuit 35 with reference to threshold level Q corresponding to the lower end position of the line most suitable for the fatigue test, masking circuit 45 for masking the average luminance levels using the binary data obtained by circuit 44, maximum level position detection circuit 36 for detecting a maximum level position from the masked data, and line lower end position detection circuit 47 for detecting a line lower end position from the maximum level position detected by circuit 36 and the masked data.
  • Line detection means 32A detects the line lower end position as follows.
  • horizontal integrating circuit 35 calculates an integrated value of a luminance level of the video signal from each raster. More specifically, in an image shown in Fig. 9(a), integrated values of the luminance levels in the same direction as that of line 13 are calculated and their averaged values are then calculated. In this way, a vertical distribution of the luminance levels shown in Fig. 9(b) can be obtained.
  • the averaged luminance levels are supplied to binary circuit 44, and are coded into binary data using threshold value Q corresponding to the line lower end position. Thus, the binary data shown in Fig. 9(c) is obtained.
  • masking circuit 45 the averaged luminance levels are masked by the binary data, thereby obtaining data shown in Fig.
  • Line lower end position detection circuit 47 receives the masked data shown in Fig. 9(d) and the data of maximum high-level position P to detect line lower end position F as a memory address corresponding thereto.
  • an averaged luminance level for each raster in the same direction is obtained from the video signal obtained by scanning test piece 10 with line 13 during the fatigue test.
  • the averaged luminance levels are binary-coded using threshold level Q corresponding to a position most suitable for the fatigue test in the widthwise direction of the line.
  • the averaged luminance levels are masked by the binary data. Therefore, the lower end position of line 13 most suitable for the fatigue test can be reliably detected.
  • the position of line 13 can be detected not as the lower end but as an upper end position of the line width in accordance with fatigue test conditions.
  • threshold level Q is decreased not to pick up a noise component of the video signal, the lower and upper end positions of the line can be more precisely detected.
  • Test piece 10 with line 13 as a reference line shown in Fig. 2 is placed on the fatigue test machine and a load is repetitively applied thereto to form crack 12. Note that this load has an amplitude of several hundreds of microns and a frequency of about 30 Hz. When such a load is applied, the surfaces of test piece 10 are illuminated and are scanned by ITV cameras 22 and 23 through microscopes.
  • test piece 10 since test piece 10 is illuminated with continuous light, the resultant image of test piece 10 is blurred.
  • the load has an amplitude of several hundreds of microns and a frequency of about 30 Hz.
  • the fields of view of ITV camera heads 22 and 23 must be several millimeters, taking a resolution into consideration. Therefore, if the test piece 10 is scanned using continuous illumination, the resultant image is blurred due to vibration of piece 10, and the position of crack distal end 12a cannot be precisely detected.
  • the width of crack 12 formed in test piece 10 varies from several microns to several tens of microns in accordance with internal and surface conditions of piece 10. A portion of crack 12 having a small width must be illuminated at an appropriate illuminance, and if not, it cannot be scanned or detected.
  • a fatigue crack position detection apparatus which can be free from image blurring and can accurately detect a crack distal end position without being blurred if a vibrating test piece is scanned can be provided.
  • a fatigue crack position detection apparatus characterized by comprising: scanning means for scanning a reference line and a crack in a notched test piece with the reference line for obtaining a crack distal end position within an identical field of view; a strobe illumination device for irradiating the notched test piece with illumination light; illumination control means for controlling an emission timing of the strobe illumination device to a predetermined timing; reference line detection means for integrating luminance levels from a video signal obtained by a scanning operation of the scanning means in the same direction as that of the reference line to obtain a maximum level to detect a reference line position; crack distal end position detection means for binary-coding the luminance levels of the video signal output from the scanning means in a direction perpendicular to a direction of the crack and thereafter discriminating continuity of a high-level value to detect a crack distal end position; and crack distal end position calculating means for calculating a distance between the reference line position obtained by the reference line detection means and the crack distal end position obtained by the crack distal end
  • the apparatus of this embodiment comprises the above-mentioned means, when a notched test piece is illuminated with light from the strobe illumination device, the notched test piece is scanned, and the reference line and the crack distal end position are detected from the resultant video signal to calculate the distance between the reference line and the crack distal end position.
  • reference numerals 50 and 51 denote strobe illumination devices, which illuminate the surfaces of test piece 10 from positions inclined with respect to optical axes G of microscopes 20 and 21 at a predetermined angle ⁇ , e.g., 30°.
  • Strobe illumination devices 50 and 51 emit light at time intervals sufficient to attenuate after-images in ITV camera heads 22 and 23.
  • an illumination control means comprises frequency divider 54 for dividing the sync signal from sync signal generator 34 for supplying the sync signal at a predetermined frequency division ratio, and strobe controllers 52 and 53 for causing strobe illumination devices 50 and 51 to emit light in response to the frequency-divided output from frequency divider 54.
  • camera switch 31 alternately passes the video signals from ITV camera heads 22 and 23 in synchronism with the emission operations of strobe illumination devices 50 and 51 in response to the frequency-divided output from frequency divider 54.
  • ITV camera heads 22 and 23 start a scanning operation under the control of ITV camera controllers 24 and 25, respectively, and generate video signals.
  • the sync signal is frequency-divided by frequency divider 54, and is output as a frequency-divided signal having a cycle twice an after-image time of ITV camera heads 22 and 23. Therefore, when the frequency-divided signal is alternately supplied to strobe controllers 52 and 53, strobe illumination devices 50 and 51 alternately emit light in synchronism with the frequency-divided signal. Strobe illumination devices 50 and 51 emit light at time intervals longer than the after-image time of ITV camera heads 22 and 23. Upon emission of strobe illumination device 50 or 51, the video signal is supplied to line detection means 32 and crack distal end detection means 33 through camera switch 31.
  • an image is intermittently displayed on display 41 since it is obtained when strobe illumination devices 50 and 51 emit light. Therefore, if an image memory is added to store image data for one frame, a surface image of test piece 10 can be displayed as a still image, and an operator can be free from inconvenience during monitoring.
  • notched test piece 10 when notched test piece 10 is illuminated with strobe illumination light from strobe illumination devices 50 and 51, it is scanned by ITV camera heads 22 and 23. Line 13 and crack distal end position 12a are detected from the resultant video signals to calculate the distance therebetween. Therefore, crack distal end position 12a can be accurately measured without blurring the scanned image of notched test piece 10. Since test piece 10 is scanned at an instant when illumination devices 26 and 27 emit light, an image can be obtained without being blurred even if test piece 10 vibrates. In addition, since emission timings of strobe illumination devices 50 and 51 are set to be longer than the after-image time of ITV camera heads 22 and 23, measurement can be free from an influence of an after-image.

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Claims (6)

  1. Verfahren zum Detektieren einer Ermüdungsrißposition an einem gekerbten Probekörper (10), das die Schritte des Beleuchtens des genannten Probekörpers (10) mit Strahlung unter einem Einfallwinkel und des Detektierens der Leuchtdichte des reflektierten Lichts aufweist,
    gekennzeichnet durch folgende Schritte: Integrieren von Leuchtdichtepegeln in der gleichen Richtung wie die einer Bezugslinie (13), die an dem genannten Probekörper angebracht ist, aus einem Bildsignal, das durch Abtasten der genannten Bezugslinie (13) und eines in dem gekerbten Probekörper (10) gebildeten Risses (12) erhalten ist, mit der Bezugslinie (13), Erhalten einer Bezugslinienposition aus einem maximalen Leuchtdichtepegel (Fig. 4b, 9b), Umwandeln des Bildsignals in ein Binärsignal, Detektieren einer distalen Endposition (12a) des Risses durch Diskriminieren der Kontinuität eines Hochpegelwerts des Binärsignals und Berechnen einer Entfernung zwischen der Bezugslinienposition und der distalen Endposition des Risses.
  2. Verfahren zum Detektieren einer Ermüdungsrißposition nach Anspruch 1, das ferner folgende Schritte aufweist: Berechnen von mittleren Leuchtdichtepegeln in der gleichen Richtung wie die einer Bezugslinie aus einem Bildsignal, das durch Abtasten eines gekerbten Probekörpers mit der Bezugslinie während einer Ermüdungsprüfung erhalten ist, Binärcodieren der mittleren Leuchtdichtepegel unter Verwendung eines Schwellenwerts, der einer Position entspricht, die für die Ermüdungsprüfung in einer Breitenrichtung der Bezugslinie (12) geeignetsten ist, und Maskieren der mittleren Leuchtdichtepegel durch die binär codierten Daten, um die Position zu detektieren, die für das Detektieren von Ermüdung am geeignetsten ist.
  3. Vorrichtung zum Detektieren einer Ermüdungsrißposition, die eine Beleuchtungseinrichtung (26, 27) und Abtasteinrichtungen (22, 23) aufweist, um die Leuchtdichte des Lichts abzutasten, das von der abzutastenden Oberfläche reflektiert wird,
    gekennzeichnet durch eine Abtasteinrichtung, die vorgesehen ist, um eine Bezugslinie (13) und einen Riß (12) in einem gekerbten Probekörper (10) abzutasten, um eine distale Endposition (12a) des Risses innerhalb eines identischen Gesichtsfelds zu erhalten, wobei die genannte Bezugslinie (13) an dem genannten Probekörper angebracht ist; eine Bezugslinien-Detektiereinrichtung (32; 32A), um Lichtdichtepegel aus einem Bildsignal, das durch eine Abtastoperation der Abtasteinrichtungen (22, 23) in der gleichen Richtung wie die der Bezugslinie (13) erhalten ist, zu integrieren, um einen Maximalpegel zu erhalten, um eine Bezugslinienposition zu detektieren; eine Einrichtung (33) zum Detektieren der distalen Endposition des Risses, um die Leuchtdichtepegel des Bildsignalausgangs von den Abtasteinrichtungen (22, 23) in einer Richtung senkrecht zu der Richtung des Risses (12) binär zu codieren und danach die Kontinuität eines Hochpegelwerts zu diskriminieren, um eine distale Endposition (12a) des Risses zu detektieren; und eine Recheneinrichtung (40) für die distale Endposition des Risses, um eine Entfernung zwischen der Bezugslinienposition, die durch die Bezugslinien-Detektiereinrichtung (32; 32A) erhalten ist, und der distalen Endposition (12a) des Risses, die durch die Einrichtung (33) zum Detektieren der distalen Endposition des Risses erhalten ist, zu berechnen.
  4. Vorrichtung zum Detektieren einer Ermüdungsrißposition nach Anspruch 3, die ferner aufweist: eine Strobe-ImpulsBeleuchtungseinrichtung (50, 51), um den gekerbten Probekörper (10) mit Beleuchtungslicht zu bestrahlen, und eine Beleuchtungssteuereinrichtung (52, 53), um einen Emissionszeitpunkt der Strobe-Impuls-Beleuchtungseinrichtung (50, 51) auf einen vorbestimmten Zeitpunkt zu steuern.
  5. Vorrichtung zum Detektieren einer Ermüdungsrißposition nach Anspruch 4, wobei die Strobe-Impuls-Beleuchtungseinrichtung (50, 51) angeordnet ist, um unter einem vorbestimmten Winkel zu einer Oberfläche des gekerbten Probekörpers (10) geneigt zu sein, um durch den Riß (12) und die Bezugslinie (13) unregelmäßiges reflektiertes Licht zu erzeugen.
  6. Vorrichtung zum Detektieren einer Ermüdungsrißposition nach Anspruch 4 oder 5, wobei die Beleuchtungssteuereinrichtung (52, 53) die Strobe-Impuls-Beleuchtungseinrichtung (50, 51) veranlaßt, mit einem Zeitintervall, das länger als eine Nachabbildzeit der Abtasteinrichtungen (22, 23) ist, Licht zu emittieren.
EP86900849A 1985-01-25 1986-01-24 Anordnung zum nachweis von durch ermüdung verursachten rissen Expired - Lifetime EP0210278B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP12098/85 1985-01-25
JP1209885A JPS61170603A (ja) 1985-01-25 1985-01-25 疲労試験片クラック先端位置の自動測定方法およびその装置
JP239026/85 1985-10-25
JP23902685A JPS6298203A (ja) 1985-10-25 1985-10-25 疲労試験片の基準線検出方法
JP23902585A JPS6298202A (ja) 1985-10-25 1985-10-25 疲労試験片クラック先端位置検出装置
JP239025/85 1985-10-25

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EP0210278A4 EP0210278A4 (de) 1988-06-27
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US4716459A (en) 1987-12-29
DE3688268D1 (de) 1993-05-19
EP0210278A1 (de) 1987-02-04
WO1986004410A1 (en) 1986-07-31

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